Hydrogen Peroxide water + oxygen
Catalse is found in potato cells, chopping up potato releases more Catalse from the cells.
Catalse is the fastest enzyme; water and oxygen are formed as a product from the reaction of Catalse and hydrogen peroxide in the cells. Hydrogen Peroxide can be poisonous if it builds up, that’s why it’s broken down.
Prediction:
I predict that as the temperatures increase, the rate of reaction will also increase. i.e. more oxygen will be given off. I also predict that beyond a certain temperature the reaction will not increase anymore, but instead it will decrease, so does the rate of reaction and substrate.
However, very high temperatures damage the enzyme by denaturing them. i.e. changing its shape, its properties and its characteristics.
The kinetic theory says that with increasing temperatures molecules have more energy causing them to speed their movement. That means that the enzyme and substrate molecules will meet more often and this will cause an increase in the product that is formed. As the temperatures continues to increase, the ionic bonds and the hydrogen which keeps the enzyme in shape breakdown. The enzyme can no longer turn the substrate into the product, the enzyme is then said to be damages into the product, the enzyme is then said to be damaged or denatured. This cannot be reversed.
This what I think my graph will look like:
Variables:
Independent variable :
Changing temperatures of hydrogen peroxide.
Dependant variable :
Height of bubbles after the reaction is over.
Control variables :
- Time reaction left for (60 seconds).
- Room temperature (about 23 C).
- Amount of potato added to hydrogen peroxide.(2 g)
- Amount of hydrogen peroxide added to potato.(20 ml)
- Same person doing all the testing.
- Testing must be done on the same day.
- Same apparatus must be used all the time.
Safety:
I have to be careful when using the hydrogen peroxide, which is a corrosive chemical, so I will avoid this by wearing this by wearing safety goggles. Hydrogen Peroxide is also a bleaching agent, so I will be wearing a lab coat so it doesn’t bleach my cloths. I will also be using sharp razors during the experiment so I will have to be careful with it.
Apparatus:
- Measuring cylinder.(100 ml cylinder)
- Electronic scale that measures to the nearest 0.01 grams
- A sharp razor.
- 1 Potato.
- Hydrogen peroxide of different temperatures.
- Small crushing dish.
- Stop watch that measures to the nearest 0.01 seconds.
Method:
- Set apparatus ready.
- Cut small pieces of potato weighting 2 grams each (make sure that you cut all the pieces from the same part of the potato, because some parts of the potato tend to have more Catalse than other parts.)
- To check that all the pieces weigh 2 grams, put each piece on the electronic scale.
- Crush each piece in the crushing dish; make sure all crushed pieces are kept separate from the other pieces.
- Measure 20 ml of hydrogen peroxide in the measuring cylinder (make sure the measuring cylinder is at your eye level to be accurate).
- Get stop watch ready
- Mix the crushed potatoes with the hydrogen peroxide in the measuring cylinder.
- Press on the start button as soon as the potatoes touch the hydrogen peroxide, you have to be accurate.
- Leave the reaction going for 60 seconds.
- Take the measure of the new reading shown on the measuring cylinder right after you stop the timing at 60 seconds.
- Subtract the measure you took from 20 ml (Which is the amount of hydrogen peroxide we started with). To get the volume of the reacted bubbles.
- Record the results.
- Throw out the chemical and wash the apparatus carefully.
- Do this for all the temperatures of the hydrogen peroxide.
- Repeat the experiment till you are satisfied with its accuracy.
Results:
Average Results:
Analysis:
My results and graph show that the reaction is fastest at its optimum temperature which in this case is 29 C, as the temperature increase or decreases from the point the rate of reaction decreases and it takes more time to react.
When we had the hydrogen peroxide at a temperature of 29 C the volume of the bubbles was 9 ml. At the temperature of 50C the volume of bubbles decreased to 4.5 ml. Also at a temperature of 20 C the volume of bubble, decreases to 5.5 ml. where at a temperature of 5 C we had an unchanging result of 1 ml of bubbles.
My prediction was correct. As the temperature of the hydrogen peroxide increased the rate of reaction and the activation energy also increased, but that is only present till a certain temperature. After that point the rate of reaction won’t increase, but instead it will decrease rapidly as you continue increasing the temperature.
This is because as you increase the temperature increases so does the rate of reaction and substrate. However, very high temperatures damage the enzyme by denaturing them. Which means that this is going to change its shape, its properties, and its characteristics of the enzyme, which would decrease its rate of reaction. Another reason of decrease of rate of reaction is that the substrate wouldn’t be able to go in the enzyme since it has changes its shape, and the key wouldn’t be suitable for the lock. Therefore there would be less products produced.
This is all based on the kinetic theory, which says that with increasing temperatures molecules have more energy causing them to speed their movement. That means that the enzyme and substrate molecules will meet more often and this will cause an increase in the product that is formed. As the temperatures continues to increase, the ionic bonds and the hydrogen which keeps the enzyme in shape breakdown. The enzyme can no longer turn the substrate into the product, the enzyme is then said to be damages into the product, the enzyme is then said to be damaged or denatured. This cannot be reversed.
Evaluation:
I think that I carried out the method accurately, and I felt my results were fairly accurate. As my graphs produced by the results I had found were fairly similar to the graph that I had predicted in my prediction.
I think the reason for this was because I: used two repeats of the experiment and an average result (which cancelled anomalies, which I think didn’t occur) which I think were sufficient. I used accurate measuring facilities. E.g. an electronic scale that measured to the nearest 0.01 grams. a measuring cylinder that measured to the nearest 1 ml, which helped me to have no problem with accuracy.
I had a reliable method, which helped me to obtain accurate results.
I think I had reliable results, which my graphs show. My results were all similar in the different sets of results and graphs.
The problem I had with measuring bubbles after the reaction was that it was very hard to measure bubbles were some used to collapse, the bubbles didn’t have a constant volume were some were very small and some were big.
I could improve the experiment by using a bigger range of temperatures so I can compare my results more accurately and discuss any faults I had. Or increasing the time the reaction is left for, to see if the reaction is going to stop after a certain period of time. Or changing the amount of potato added to the hydrogen peroxide. Or changing the amount of hydrogen peroxide added to the potato to see if this is going to affect the reaction.
I could even stop using the temperature of the hydrogen peroxide as a variable and start a new experiment using the P.H. of the hydrogen peroxide as a variable.
One thing I could do is changing the dependant variable, which is the height of the bubbles produced after the reaction because it’s very hard to measure as I mentioned before.
